# coding: utf-8
# Your code here!

import math
x1, y1, x2, y2 = map(float, input().split())
result = math.sqrt( (x2-x1) * (x2-x1) + (y2-y1) * (y2-y1) )
print(result) import math math x1, y1, x2, y2 = map(float, input().split()) x1 map(float, input().split()) map float input().split() ().split () input split y1 x2 y2 result = math.sqrt( (x2-x1) * (x2-x1) + (y2-y1) * (y2-y1) ) result math.sqrt( (x2-x1) * (x2-x1) + (y2-y1) * (y2-y1) ) math.sqrt math sqrt (x2-x1) * (x2-x1) + (y2-y1) * (y2-y1) (x2-x1) * (x2-x1) x2-x1 x2 x1 x2-x1 x2 x1 (y2-y1) * (y2-y1) y2-y1 y2 y1 y2-y1 y2 y1 print(result) print result x1, y1, x2, y2 = map(float, input().split()) map(float, input().split()) x1 y2 = map(float, input().split()) map(float, input().split()) y2 result = math.sqrt( (x2-x1) * (x2-x1) + (y2-y1) * (y2-y1) ) math.sqrt( (x2-x1) * (x2-x1) + (y2-y1) * (y2-y1) ) result x2, y2 = map(float, input().split()) map(float, input().split()) x2 y1, x2, y2 = map(float, input().split()) map(float, input().split()) y1
# coding: utf-8
# Your code here!

import math
x1, y1, x2, y2 = map(float, input().split())
result = math.sqrt( (x2-x1) * (x2-x1) + (y2-y1) * (y2-y1) )
print(result)
